scholarly journals Gravitational waves and dark photon dark matter from axion rotations

2021 ◽  
Vol 2021 (12) ◽  
Author(s):  
Raymond T. Co ◽  
Keisuke Harigaya ◽  
Aaron Pierce
Keyword(s):  
Dark Matter ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
Early Universe ◽  
Radial Direction ◽  
Particle Production ◽  
Baryon Asymmetry ◽  
Complex Field ◽  
Dark Photon ◽  
Pulsar Timing

Abstract An axion rotating in field space can produce dark photons in the early universe via tachyonic instability. This explosive particle production creates a background of stochastic gravitational waves that may be visible at pulsar timing arrays or other gravitational wave detectors. This scenario provides a novel history for dark photon dark matter. The dark photons may be warm at a level detectable in future 21-cm line surveys. For a consistent cosmology, the radial direction of the complex field containing the axion must be thermalized. We explore a concrete thermalization mechanism in detail and also demonstrate how this setup can be responsible for the generation of the observed baryon asymmetry.

scholarly journals Modern Topics in Scalar Field Cosmology

2020 ◽  
Author(s):  
◽  
Cari Powell
Keyword(s):  
Dark Matter ◽  
Scalar Field ◽  
Gravitational Wave ◽  
Gravitational Waves ◽  
Mass Range ◽  
Distant Future ◽  
Field System ◽  
Stochastic Background ◽  
Scalar Field Cosmology

The aim of this research is to use modern techniques in scalar field Cosmol-ogy to produce methods of detecting gravitational waves and apply them to current gravitational waves experiments and those that will be producing results in the not too distant future. In the first chapter we discuss dark matter and some of its candidates, specifically, the axion. We then address its relationship with gravitational waves. We also discuss inflation and how it can be used to detect gravitational waves. Chapter 2 concentrates on constructing a multi field system of axions in order to increase the mass range of the ultralight axion, putting it into the observation range of pul-sar timing arrays. Chapter 3 discusses non-attractor inflation which is able to enhance stochastic background gravitational waves at scales that allows them to be measured by gravitational wave experiments. Chapter 4 uses a similar method to chapter 3 and applies it to 3-point overlap functions for tensor, scalar and a combination of the two polarisations.

scholarly journals The holographic spacetime model of cosmology

2018 ◽  
Vol 27 (14) ◽  
pp. 1846005 ◽  
Author(s):  
Tom Banks ◽  
W. Fischler
Keyword(s):  
Dark Matter ◽  
Gravitational Waves ◽  
Structure Formation ◽  
Big Bang ◽  
Baryon Asymmetry ◽  
Gaussian Fluctuations ◽  
Primordial Gravitational Waves ◽  
Conventional Models ◽  
Non Gaussian ◽  
The Big Bang

This essay outlines the Holographic Spacetime (HST) theory of cosmology and its relation to conventional theories of inflation. The predictions of the theory are compatible with observations, and one must hope for data on primordial gravitational waves or non-Gaussian fluctuations to distinguish it from conventional models. The model predicts an early era of structure formation, prior to the Big Bang. Understanding the fate of those structures requires complicated simulations that have not yet been done. The result of those calculations might falsify the model, or might provide a very economical framework for explaining dark matter and the generation of the baryon asymmetry.

scholarly journals PULSAR TIMING ARRAYS

2013 ◽  
Vol 22 (01) ◽  
pp. 1341008 ◽  
Author(s):  
BHAL CHANDRA JOSHI
Keyword(s):  
Gravitational Wave ◽  
Gravitational Waves ◽  
Low Frequency ◽  
Radio Pulsars ◽  
Very Low Frequency ◽  
Pulsar Timing ◽  
Gravitational Wave Background ◽  
Pulsar Timing Array ◽  
Current Operating

In the last decade, the use of an ensemble of radio pulsars to constrain the characteristic strain caused by a stochastic gravitational wave background has advanced the cause of detection of very low frequency gravitational waves (GWs) significantly. This electromagnetic means of GW detection, called Pulsar Timing Array (PTA), is reviewed in this paper. The principle of operation of PTA, the current operating PTAs and their status are presented along with a discussion of the main challenges in the detection of GWs using PTA.

scholarly journals Gravitational waves from an axion-dark photon system: A lattice study

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Wolfram Ratzinger ◽  
Pedro Schwaller ◽  
Benjamin Stefanek
Keyword(s):  
Numerical Simulation ◽  
Dark Matter ◽  
Early Universe ◽  
Degree Of Polarization ◽  
Dark Photon ◽  
System A ◽  
Precise Prediction ◽  
Relic Abundance ◽  
Vast Range ◽  
Photon Coupling

In this work, we present a lattice study of an axion - dark photon system in the early Universe and show that the stochastic gravitational wave (GW) background produced by this system may be probed by future GW experiments across a vast range of frequencies. The numerical simulation on the lattice allows us to take into account non-linear backreaction effects and enables us to accurately predict the final relic abundance of the axion or axion-like particle (ALP) as well as its inhomogeneities, and gives a more precise prediction of the GW spectrum. Importantly, we find that the GW spectrum has more power at high momenta due to 2\rightarrow12→1 processes. Furthermore, we find the degree of polarization of the peak of the GW spectrum depends on the ALP-dark photon coupling and that the polarization can be washed out or even flipped for large values thereof. In line with recent results in the literature, we find the ALP relic abundance may be suppressed by two orders of magnitude and discuss possible extensions of the model that expand the viable parameter space. Finally, we discuss the possibility to probe ultralight ALP dark matter via spectral distortions of the CMB.

scholarly journals Probing dark matter clumps, strings and domain walls with gravitational wave detectors

2021 ◽  
Vol 81 (9) ◽  
Author(s):  
Joerg Jaeckel ◽  
Sebastian Schenk ◽  
Michael Spannowsky
Keyword(s):  
Dark Matter ◽  
Gravitational Wave ◽  
Domain Walls ◽  
Matter Power Spectrum ◽  
Pulsar Timing ◽  
Astrophysical Objects ◽  
Gravitational Wave Interferometer ◽  
Moderate Sensitivity ◽  
Gravitational Pull ◽  
Square Kilometer Array

AbstractGravitational wave astronomy has recently emerged as a new way to study our Universe. In this work, we survey the potential of gravitational wave interferometers to detect macroscopic astrophysical objects comprising the dark matter. Starting from the well-known case of clumps we expand to cosmic strings and domain walls. We also consider the sensitivity to measure the dark matter power spectrum on small scales. Our analysis is based on the fact that these objects, when traversing the vicinity of the detector, will exert a gravitational pull on each node of the interferometer, in turn leading to a differential acceleration and corresponding Doppler signal, that can be measured. As a prototypical example of a gravitational wave interferometer, we consider signals induced at LISA. We further extrapolate our results to gravitational wave experiments sensitive in other frequency bands, including ground-based interferometers, such as LIGO, and pulsar timing arrays, e.g. ones based on the Square Kilometer Array. Assuming moderate sensitivity improvements beyond the current designs, clumps, strings and domain walls may be within reach of these experiments.

scholarly journals Principles of Gravitational-Wave Detection with Pulsar Timing Arrays

Symmetry ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 2418
Author(s):  
Michele Maiorano ◽  
Francesco De Paolis ◽  
Achille A. Nucita
Keyword(s):  
Gravitational Wave ◽  
Gravitational Waves ◽  
Low Frequency ◽  
Black Hole Binaries ◽  
Pulsar Timing ◽  
Time Correlations ◽  
Array Detection ◽  
Square Kilometer Array ◽  
Gravitational Wave Background ◽  
Pulsar Timing Array

Pulsar timing uses the highly stable pulsar spin period to investigate many astrophysical topics. In particular, pulsar timing arrays make use of a set of extremely well-timed pulsars and their time correlations as a challenging detector of gravitational waves. It turns out that pulsar timing arrays are particularly sensitive to ultra-low-frequency gravitational waves, which makes them complementary to other gravitational-wave detectors. Here, we summarize the basics, focusing especially on supermassive black-hole binaries and cosmic strings, which have the potential to form a stochastic gravitational-wave background in the pulsar timing array detection band, and the scientific goals on this challenging topic. We also briefly outline the recent interesting results of the main pulsar timing array collaborations, which have found strong evidence of a common-spectrum process compatible with a stochastic gravitational-wave background and mention some new perspectives that are particularly interesting in view of the forthcoming radio observatories such as the Five hundred-meter Aperture Spherical Telescope, the MeerKAT telescope, and the Square Kilometer Array.

scholarly journals CMB anisotropy science: a review

2012 ◽  
Vol 8 (S288) ◽  
pp. 42-52 ◽  
Author(s):  
Anthony Challinor
Keyword(s):  
Dark Matter ◽  
Cosmological Model ◽  
Cosmic Microwave Background ◽  
Gravitational Waves ◽  
Early Universe ◽  
Critical Role ◽  
Microwave Background ◽  
Fundamental Physics ◽  
Standard Cosmological Model

AbstractThe cosmic microwave background (CMB) provides us with our most direct observational window to the early universe. Observations of the temperature and polarization anisotropies in the CMB have played a critical role in defining the now-standard cosmological model. In this contribution we review some of the basics of CMB science, highlighting the role of observations made with ground-based and balloon-borne Antarctic telescopes. Most of the ingredients of the standard cosmological model are poorly understood in terms of fundamental physics. We discuss how current and future CMB observations can address some of these issues, focusing on two directly relevant for Antarctic programmes: searching for gravitational waves from inflation via B-mode polarization, and mapping dark matter through CMB lensing.

scholarly journals Constraining the nanohertz gravitational wave background with the Parkes Pulsar Timing Array

2012 ◽  
Vol 8 (S291) ◽  
pp. 177-177
Author(s):  
Ryan Shannon
Keyword(s):  
Gravitational Wave ◽  
Gravitational Waves ◽  
Direct Detection ◽  
Massive Black Hole ◽  
Black Hole Binaries ◽  
Pulsar Timing ◽  
The Galaxy ◽  
Gravitational Wave Background ◽  
Pulsar Timing Array ◽  
The Universe

AbstractThe direct detection of gravitational waves will usher in a new era of astrophysics, enabling the study of regions of the universe opaque to electromagnetic radiation or electromagnetically quiet. An ensemble of pulsars (referred to as a pulsar timing array) provides a set of clocks distributed across the Galaxy sensitive to gravitational waves with periods on the order of five years (frequencies of many nanohertz). Plausible source of gravitational waves in this frequency band include massive black hole binaries in the throes of mergers and oscillating cosmic strings. The stochastic gravitational wave background, the sum of gravitational waves emitted throughout the universe, is the most likely signal to be detected by a pulsar timing array.While the detection of gravitational waves will be a milestone in pulsar astronomy, a constraining limit on the strength of the gravitational wave background can be used to constrain cosmological models and early Universe physics. Here we present a new algorithm that can be used to constrain the strength of the GWB with a pulsar timing array. We then apply this technique to Parkes Pulsar Timing Array observations and place a new limit on the strength of the GWB. We conclude by discussing the astrophysical implications of this limit and the prospects for detecting gravitational waves with pulsars.

scholarly journals Effects of gravitational waves on the polarization of pulsars

2016 ◽  
Vol 31 (02n03) ◽  
pp. 1641023 ◽  
Author(s):  
Shahen Hacyan
Keyword(s):  
Gravitational Wave ◽  
Gravitational Waves ◽  
Electromagnetic Waves ◽  
Stokes Parameters ◽  
Polarization Angle ◽  
Stochastic Background ◽  
Pulsar Timing

The polarization of electromagnetic waves in the presence of a gravitational wave is analyzed. The rotation of the polarization angle and the Stokes parameters are deduced. A possible application to the detection of stochastic background of gravitational waves is proposed as a complement to the pulsar timing method.

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